Second desalination plant for coast
Namibia has the largest desalination plant in Southern Africa, with a capacity of 20 million cubic metres per year, and a second one is going to be built to provide for the water demand at the coast.The existing desalination plant is located outside Swakopmund and augments the freshwater supply to four towns and several mines in the vicinity.
Agriculture minister Calle Schlettwein said this at the Cairo Water Week taking place in Egypt.
Schlettwein said about 12 million cubic metres of water is supplied from the desalination plant, along with nine million cubic metres of water that is abstracted from two alluvial groundwater aquifers in the Kuiseb and Omaruru rivers.
The plant is owned by Orano, who originally built it to supply their uranium mine with water. The mine, however, never operated due to the uranium price crash after the meltdown at Fukushima. Schlettwein said NamWater, that operates the Orano plant, has a water take-off agreement in place.
He said the bulk water tariff for desalinated water stands at N$41.70 per cubic metre, whereas the tariff for water from groundwater aquifers stands at N$12.4. After it is blended, this price increases to N$14.87.
“The plant is, however, unreliable since it has frequent shut-downs due to sulphur outbreaks in the ocean, resulting in massive mussel die-off and consequent blocks of the intake.”
Bigger demand
Schlettwein said Namibia has embarked on establishing stand-alone solar-powered desalination plants to treat salty or brackish groundwater in areas where no other fresh water is available.
A second 20 million cubic metre desalination plant will be built to supply the coast and mines in the vicinity with fresh water.
“Current demand stands at about 14 million cubic metres per year, but new mines and population growth are estimated to increase the demand to double within the next 10 years.”
He said the power supply for this plant is hybrid, from the grid and from a dedicated photovoltaic (PV) plant.
“Desalination for hydrogen production holds the potential to bring down the cost of desalinated domestic and agricultural uses through cross-subsidisation, an approach Namibia is pursuing. The current green hydrogen pilot project will produce a 2 million cubic metre surplus, which will be made available for domestic use at no cost.”
Reclamation
Schlettwein said originally the water reclamation plant in Windhoek had a production potential of about 35% of the overall drinking water supply for the City of Windhoek.
Production fell back to about 24%, or 5.84 million cubic metres per year, however, due to increased demand about the production capacity of the plant and slowing filtration through the fine sand filters.
He said the system is in the process of being upgraded by adding a second plant to reach an enhanced total capacity of 30% of drinking water demand, equal to 13.4 million cubic metres of water, once completed.
“This upgrade requires a revamp of the existing sewage works as well as sewage feeder lines into the plants.”
The project is jointly funded by Namibia's resources and Germany’s KfW development bank.